An X-ray fluorescence spectrometer has been known as an instrument for measuring elements contained in a sample and the concentration of the elements. The X-ray fluorescence spectrometer is configured to detect fluorescent X-rays emitted from a sample when the sample is irradiated with X-rays and analyze constituent elements based on the energy and an intensity of the fluorescent X-rays.
An energy-dispersive X-ray fluorescence spectrometer and a wavelength-dispersive X-ray fluorescence spectrometer have been widely used as the X-ray fluorescence spectrometer. The energy-dispersive X-ray fluorescence spectrometer is equipped with an energy-dispersive detector and can analyze all the elements at the same time. The wavelength-dispersive X-ray fluorescence spectrometer is configured to disperse X-rays using a spectroscopic device for each element and can perform analysis more accurately compared to the energy-dispersive spectrometer.
Specifically, the wavelength-dispersive X-ray fluorescence spectrometer has an energy resolution of about 10 eV through the use of the spectroscopic device. Meanwhile, the energy-dispersive X-ray fluorescence spectrometer without using the spectroscopic device performs analysis through the use of a semiconductor detector, for example, a silicon drift detector (SDD) having an energy resolution of about 100 eV.
In the energy-dispersive spectrometer, there are a larger number of peak overlaps of measurement lines and a background intensity is higher compared to the wavelength-dispersive spectrometer. Therefore, in general, the energy-dispersive spectrometer removes the background intensity by, for example, waveform separation processing and extracts only a peak intensity to thereby perform quantitative analysis.
Meanwhile, in the wavelength-dispersive spectrometer, separation and removal of a background intensity are not performed in general since the influence of the background intensity is smaller compared to the energy-dispersive spectrometer. However, when performing high-accuracy analysis, for example, quantitative analysis of minor components, separation and removal of the background intensity are performed through the use of the wavelength-dispersive spectrometer in some cases.
For example, in a general sequential spectrometer configured to perform scanning with a goniometer through interlocking of a spectroscopic device and a detector, a background intensity is measured at around a peak region by moving the goniometer under the assumption that the sensitivity of the measurement of the background at the peak region is almost the same as that at around the peak region and then quantitative analysis is performed by subtracting the background intensity from a measured peak intensity. In this case, it takes a long period of time for the measurement.
Further, in JP 10-206356 A, there is the following disclosure. Both a detector configured to measure secondary X-rays from a sample dispersed by a spectroscopic device and an energy-dispersive detector configured to directly measure the secondary X-rays from the sample without dispersing the secondary X-rays are mounted in a wavelength-dispersive spectrometer, and the detectors to be used are switched in accordance with the application.
However, the configuration including both the energy-dispersive detector configured to directly measure the secondary X-rays from the sample without dispersing the secondary X-rays and the detector configured to measure the secondary X-rays dispersed by the spectroscopic device increases the complexity of the instrument.
In view of the foregoing, for example, in JP 2000-292382 A and JP 2000-329714 A, as an X-ray fluorescence spectrometer having a simple device configuration, there is a disclosure of an X-ray fluorescence spectrometer including both a spectroscopic device configured to disperse secondary X-rays and an energy-dispersive detector configured to measure the dispersed X-rays. For example, this spectrometer is configured to first directly measure secondary X-rays emitted from a sample and obtain a full energy spectrum in a short period of time, and then measure the dispersed secondary X-rays. Accordingly, the spectrometer individually measure fluorescent X-rays of minor elements and fluorescent X-rays that cannot be separated from an interfering line without being dispersed.
Further, a technology of removing the above-mentioned background intensity is, for example, described in the following JP 2008-256698 A. An X-ray intensity within a narrow energy range is measured while secondary X-rays dispersed by a spectroscopic device are scanned with an energy-dispersive detector over a wide spectroscopic angle (energy) range. A background intensity due to interference of, for example, neighboring lines and higher-order X-rays at a peak angle (energy) is estimated based on the measured X-ray spectrum, and the estimated background intensity is subtracted from a measured peak in the X-ray spectrum.